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L. W. DOWNES. METHOD 0E AND APPARATUS 4EQE INSULATTNG ELECTRICAL GONDUGTOES; No. 534,785. Patented F6526, 1895.

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L. W. DOWNBS. A METHOD 0E AND APPARATUS EOE TNSULATlNG ELECTRICAL ooNDUGToEs.

No. 584,785. Patented Feb. 26, 1,895.

V ITED TATES PATENT OFFICE.

LOUIS W. DOVVNES, OF PROVIDENCE, RHODE ISLAND.

METHOD 0F D'APPARATUS FOR lNSUL/lTlNG ELECTRICAL CONDUCTORS.

SPECIFICATION forming part of Letters Patent No. 534,785, dated February 26, 1895.

Application filed August 22. 1894. Serial No. 521.029. (No model.)

To a/ZZ whom t may concern.-

Be it known that I, LOUIS W. DOWNEs, of Providence, Rhode Island, have invented a new and useful Improvement in Methods of and Apparatus for Insulating Electrical Cone ductors, which is fully set forth in the following specification.

The present invention relates to a method of and apparatus for applying an insulating covering to electrical conductors. The said method and apparatus are specially designed for the production of an electrical conductor with an insulation composed of asbestos, and the insulated conductor produced by the new method and apparatus is included in the invention.

Heretofore, asbestos insulation has been defective and unsuitable for a great variety of uses in the electrical art because, from the nature of the substance, itis extremely difd cult to apply it to the wire in a compact, uniform and sufficiently thin coating, andin a permanent manner. The expense and bulkiness of conductors covered partly or entirely by asbestos have also stood in the way of their use.

. It has been proposed heretofore to applyan asbestos covering to a tube by Weaving or braiding (as in a whip-braiding machine) strands of asbestos fiber around a wire, but vsuch procedure has not been found successful in practice because the asbestos fibers are short and brittle, and the covering is easily abraded, and detached from the wire in handling and use. For these and like reasons asbestos-insulated Wire has not up to the present time become an articleof manufacture. The object of the present invention is to remove these ditculties, and to provide means for the manufacture of asbestos insulated conductorsat small cost and having the proporties requisite to admit of their use in armature windings, house-Wiring, and for like purposes.

According to my present invention the Wire Vafter first being coated with a quick drying adhesive mixture, such as some form of gum, 'applied thereto by any suitable means, is covered with the asbestos fiber, wound spirally or otherwise thereon, by any suitable mech# anism well known to those familiar with the art. The wire is then subjected to a finish;

ing process consisting in, first, combing or brushing out the asbestos covering to remove all superfluous lumps, irregularities, dro., and 5 5 laying the nap all in one direction; second, applying pressure to the covering whereby the fiber is matted together in a compact layer, the thickness being gradually reduced to a suitable point; third, applying a coating 6o of a water-proofing and toughening compound, to protect the insulation from injury in handling, and to impart to it moisture-resisting properties. After these operations theconductor is preferably passed again between pressure rolls and drawn through dies to impart a smooth Elnish and reduce lthe insulated conductor to an even diameter.

The brushing or carding of the asbestos fiber is an important step of the process and 7o contributes largely to the excellence of the finished product, and it is mainly to admit of this operation being successfully performed that the wire is coated with adhesive substance before applying the asbestos fiber,

since I have found it impracticable to raise the nap properly unless the fiber is applied to the Wire by the aid of an adhesiveniaterial. I therefore desire to cover broadly the improvement consisting in applying the fiber 8o by means of an adhesivesubstance and brushing, carding or raising the nap, irrespective of the precise mode adopted for finishing the product.

In order that the invention and the lbest means now known to me of applying the same in practice, may be fully understood, I will describe the same in detail With the aid of the accompanying drawings, in `which Figure l is a plan view of apparatus em- 9o ployed in carrying out the process, and which is also included in the invention. Fig, 2 is a side elevation thereof. Fig. 3 is a detail view in side elevation of the carding or brushing devices. Fig. 4 is an end elevation thereof. Fig. 5 95 is an end elevation of one set of pressure-rollsi Fig. 6 is a detail in vertical section of the rollers and their actuating mechanism. Figs. 7 and 8 are detail views representing the conductor on an enlarged scale.

In the drawings @represents the conductor having a covering of asbestos fiber applied and held thereon by means of a quick-drying adhesive gum, as already described. Inasmuch as there are appliances-in common use for Wrapping wires with fibrous material, any of which may be used for the purposes of this process, it is not necessary to give a description of such appliances.

All the moving parts Aof the machine are driven from a main shaft A through suitable gearing, as clearly shown in the drawings.

The covered wirey issubjectcd to the action of the carding or brushing devices (Figs. l and 3). These devices comprise a suitable brush or brushes b carried by adisk- B, the brush` holder b being adjustable radially of said disk by means of a screw b2. Disk B receives motion from shaft A through a spur gear C on said shaft, and a pinion c attapch'edkto' the disk. The pinion, its hub and the disk are all provided' Vwith a central passage through which the wire passes. To dislrjB isjalso secured a bracket c" upon which the wire rests while under the action of brush b; and' asthe latter rotates the nap is raised and laid allin the sanne direction', While all lur'nps and in`- equalities in the fiber are reinoved, bringing the covered conductor incre nearly to a uni-l forni diameter. Atter'passingthrough a guide Dj the wire is subjected tothe action of aserieso'f pressure rolls.. In the fnachineshown E and F in Figs. 1 and 2) but there be more or les's as desired. p The particular construction of vthese devices; is illustrated in rigsl` e and o. The disk E is mounted on the hub of a pinion. e' which receives motion from a spur gear G on the niain shaft. VTo the face of this disk lare secured three radial slides f setone hundred and twentydegrees apart and adjustable radiallyby' means of set screws f. Each slide carries at its inner end a small roll g the shafts g of these rolls being parallel with the line of travel of the wire u. The pressure of the rolls being properly regulated by the set screws, they compress and mat the asbestos fiber', reducing gradually the thickness' of the insulated conductor to a suitable point. A n D2 D5 indicate other guides through Vwhich the Wirepasses, and H indicates a take-up roll around which the wire is led, and which draws it through the napping and rolling devices. This takefup roll is' driven from a worin h -through pinion's h h2. The wire then passes between tW'o rolls 7c l by nieans of which the toughening and water-proofing compound is applied. For this purpose I may' use with advantage any suitable oil having the desired properties such as linseed. Rolls'lclare faced with felt or other absorbent substance, and they latter dips into a small tank l containing the V oil or Water proof liquid, roll lo taking a sufficient supply thereof by contact with roll Z. M, N represent two sets of finishing rolls, the axes of the two's'ets being at right angles to each other, These rolls are simply to smooth down the coating and remove the eX'- cess of oil. Finally it is passed through a ofY the reel.

Fig. 7 illustrates on an enlarged scale the appearance of the conductor u, after the first operation of4 winding the asbestos strand or thread thereon. The turns of thread are laid as close together as possible, but at this f stageeach spiral. is', of course, separate from the others. They present numerous lumps and inequalities, and their hold upon the wire and upon one another is very slight.

Fig. 8 illustrates thetinished product,-in which the separate spirals' disappear, the covering resembling a continuous' and coherent fabric, dense and sniooth and adhering with considerable tenacity tothe wire. i

Obviously many variations may be introduced in the man-ner of finishing the'product after raising vthe nap in the mannerdescribed, and in the character of the appliances used for performing the several steps of the process. It is also obviousthat 'seine ofthe steps of the process and' parts ofthe described app l, paratus may he used without others.

there are two sets of these' rolls (designated The finished product has physical characteristics which distinguish it from other iusulated conductors heretofore made orkn'ow'n.

f The covering is dense and coin-pact, the fibers beingv well rnatted' or felted together and adhering closely'tojl the wire. The surface is snioothnand` uniform and the covering very thin. I find that an effectual insulation can be produced of a thickness less than 0.01 of an inch, which is of great importance in windings for armatures and field coils. These qualities of the finished product are due to the napping and compressing of the fiber, pro'- ducingan extremely tough, dense and coherent fabric, as distinguished from a Aseries of coils with inofeor less space between them, and with an inherent tendency to separate. In point of economy the conductor compares favorably with that insulated by a braided cotton covering in common use. 1

Having thus described inyinvention, what v `1. The described process of applying a fibrousv insulating covering, such as asbestos, to an electrical conductor, which process consists incoating the conductor with an adhesive substalice, wrapping or winding the ber thereon, brushing' or carding' the latter to raise a nap and then pressing or compacting the liber, substantially as set forth.

2. In the manufacture of insulated electrical conductors, the improvement which consists in applying a fibrous covering of asbestos to the wire, brushing the fiber in one direction, and compressing and reducing it to a sinoothsurface and uniform diameter, substantially as described. Y A V 3. In the manufacture of insulated electri- IOO IIO

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cal conductors, the improvement which consists in coating a wire .with adhesive -substance, Wrapping it with fibrous asbestos, brushing out the nap in one direction, rolling the brous covering upon the Wire, and then applying thereto a water-proofing substance substantially as described.

4. The described process of manufacturing insulated electrical conductors, which process consists in coating a Wire with adhesive substance, wrapping it with brous asbestos, brushing the fibrous coating to raise the nap, compressing it between pressure rolls, coating With Waterproof material, and subjecting it to a final rolling to produce a smooth finished surface, as set forth.

5. In an apparatus for the purpose specified, the combination of devices for feeding a wire longitudinally, a rotating brush or carding device having its axis of rotation coincident with the axis of the Wire, pressure-rolls for compressing the nap raised by the brush, and rolls for applying a Water-proofing substance, substantially as described.

6. The combination with theWire-feeding mechanism, of a rotating brush for acting on the surface of the Wire as it advances, pressnre rolls having their axes parallel with the Wire, and mechanism for rotating the rolls circumferentially about thesaine as it is fed around the Wire, means for applying to the surface of the Wire a Water-proofing compound', and finishing pressure rolls, all arranged and operating substantially as described.

8. As an article of manufacture, an. electrical conductor having a compact, uniform covering of asbestos ber, Wound spirally thereon, matted compressed and Water-proofed substantially as described.

9. As an article of manufacture, an electrical conductor having a thin, compact, uniform covering of asbestos fiber Wound thereon and attached by adhesive substance, the fibers being matted and compressed into a coherent fabric, substantially as described.

In testimony whereof I have signed this specification in the presence of two subscribing Witnesses.

LOUIS W. DOI/VN ES.

Witnesses:

GILMAN E. JOPP, WM. W". RIOKARD. 

